A movable iron core linear actuators, such as a reciprocal motor, includes, as a main component, a magnetic circuit in which a moving element reciprocates when being energized as illustrated in, for example, Patent Document 1. The magnetic circuit includes an iron core constituting a moving element, a stator core including a facing portion which faces the iron core, a pair of permanent magnets disposed in a facing portion along the reciprocating direction and having inverted magnetic poles at their surfaces which face the iron core, and a coil wound around the stator core. A magnetic flux produced by energization of coil weakens a magnetic flux produced in a magnet situated in a necessary direction between the pair of permanent magnets, and strengthens a magnetic flux produced in the other magnet. Therefore, the moving element is made to reciprocate with respect to the stator core.
Further, the magnetic circuit causes the spring force of the magnetic spring, which is changed in accordance with a relative position of the moving element with respect to a stator core, to act on the moving element by the magnetic flux produced by the permanent magnets. When the coil is being energized, the spring force of the magnetic spring is superimposed on the magnetic driving force produced by the energization of the coil and is applied to the moving element.